Certain compounds containing a glutarimide moiety have been reported to show pharmaceutical properties suitable for clinical development. One example is (S)-3-(4-((4-(morpholinomethyl)benzyl)oxy)-1-oxoisoindolin-2-yl)piperidine-2,6-dione. The compound is described in U.S. Patent Publication No. 2011/0196150, which is incorporated herein by reference in its entirety.
Processes for synthesizing enantiomerically enriched or enantiomerically pure 3-(4-((4-(morpholinomethyl)benzyl)oxy)-1-oxoisoindolin-2-yl)piperidine-2,6-dione have been previously described in U.S. Patent Publication No. 2014/0046058, which is incorporated herein by reference in its entirety. The processes utilize (S)-tert-butyl 4,5-diamino-5-oxopentanoate hydrochloride as a key starting material for the construction of the (S)-2-aminoglutarimide moiety.
The synthesis of (S)-tert-butyl 4,5-diamino-5-oxopentanoate hydrochloride has been previous reported. For example, one recent report describes synthesis of (S)-tert-butyl 4,5-diamino-5-oxopentanoate hydrochloride from Cbz-(L)-Glu(tBu)-OH. J. Med. Chem. 2016, 59(19), 9107-9123 (supporting information).

This reported method, however, is not suitable for scale up. It describes removing solvent to dryness, which leads to an uncontrolled precipitation (which in turn can lead to variable purity). It also describes the use of high volumes (up to 56 volumes, i.e., 56 mL per gram), which is inefficient on large scales. Additionally, the process does not describe control of the stereogenic (chiral) center. There is no literature about the chiral purity of the products.
(S)-tert-Butyl 4,5-diamino-5-oxopentanoate hydrochloride is commercially available, normally only at gram quantities. The price normally ranges from $300 to $800 per 100 g of the product, which could be costly for large scale preparation of glutarimide-containing compounds. The delivery normally takes several weeks (e.g., about 12 weeks), and the chemical purity of the commercial product is normally reported to be about 95-98%. The analytical data for the chiral purity is often not well defined.
Despite of its current availability, a need still exists for the development of alternative synthetic processes for (S)-tert-butyl 4,5-diamino-5-oxopentanoate hydrochloride.